Objectives. The aim of this study was to examine whether asymmetric loading
influences macrophage elastase (MMP12) expression in different parts
of a rat tail intervertebral disc and growth plate and if MMP12
expression is correlated with the severity of the deformity. Methods. A wedge deformity between the ninth and tenth tail vertebrae
was produced with an Ilizarov-type mini external fixator in 45 female
Wistar rats, matched for their age and weight. Three groups were
created according to the degree of deformity (10°, 30° and 50°).
A total of 30 discs and vertebrae were evaluated immunohistochemically
for immunolocalisation of MMP12 expression, and 15 discs were analysed
by western blot and zymography in order to detect pro- and active
MMP12. Results. No MMP12 expression was detected in the nucleus pulposus. Expression
of MMP12 in the annulus progressively increased from group I to
groups II and III, mainly at the concave side. Many growth plate
chondrocytes expressed MMP12 in the control group, less in group
I and rare in groups II and III. Changes in cell phenotype and reduction
of cell number were observed, together with disorganisation of matrix
microstructure similar to disc degeneration. ProMMP12 was detected
at the area of 54 kDa and active MMP12 at 22 kDa. Conclusions. Expression of MMP12 after application of
